1. Field of the Invention
This invention relates in general to devices for protecting the threaded ends of well casing pipes.
2. Prior Art. One re-occurring problem in the drilling industry has been the damage to pipe threads during handling. It is not unusual for drill pipe to be 30-60 feet long and weigh in excess of 2000 pounds. Thus if a drill pipe is dropped or if it is bounced against another drill pipe or if it is drug across the floor of a drilling platform the threads may well become damaged. If this occurs it may be impossible to connect two adjoining pieces of drill pipe, or if joined may result in improper sealing between the joints or in a weakened joint.
Previous means for protecting the threads of drill pipe have included wrapping the threads with some type of protective coating. However these prior art devices are not easily installed or removed. Furthermore they have not allowed for drift gauging the pipe when installed on the casing. In other cases they simply have not been able to withstand the shock that can be incurred during normal handling of the drill pipe.
To overcome the deficiencies in earlier prior art devices various types of belting devices have been proposed. Such a device is disclosed and described in U S. Pat. No. 3,240,232, issued to Carrol J. Matherne on Mar. 15, 1966. Therein a thread protector is disclosed which includes a tension belt, a latching structure interconnecting the ends of the tension belt and a body of resilient material associated with the tension belt and latching structure so that the protector may be mounted on the threaded end of a pipe to allow the pipe to be gauged by a drift gauge in a well-known manner. This type of thread protector has been in use in the oil well field for some time. U.S. Pat. No. 3,038,502 issued to Ernest D. Hauk et al on Jun. 12, 1962, discloses another thread protector having generally the same components as the above-mentioned patent except that the latching device is cam operated and includes a handle structure extending diametrically of the pipe on which the protector is mounted. U.S. Pat. No. 4,036,261, issued to Ernest D. Hauk on Jul. 17, 1977, discloses another type of thread protector which is pneumatically operated. Other prior art patents relating to thread protectors are listed in the above mentioned patents. On Sep. 14, 1982 U.S. Pat. No. 4,349,048 issued to the inventor herein disclosing an improved pipe thread protector which overcame many of the problems with the other prior art devices. This thread protector incorporated an internal metal band vulcanized in the body wherein the band was rolled to an open position and heat treated to provide opening spring action. The opening and closing movement was achieved by a link and bolt assembly actuated with a handle rotation. However, there is still need for a pipe thread protector device especially useful for well casing pipe that is less likely to be damaged during the movement of the well casing pipe, as well as quicker and easier to repair, install and remove from the well casing pipe at the drill site. In addition it is desirable to provide a well casing pipe thread protector that allows thread inspection at the pipe rack on the drilling platform rather than at the well head.